United States Patent Publication No. US 2004/0032247, by Dykeman, discloses a battery charging system that provides cyclic charging pulses to a battery, wherein the charging pulse has a current component and a voltage component that varies between a quiescent voltage and a maximum voltage. The system further comprises a battery monitoring circuit adapted to monitor one or more of the battery's parameters that respond to the charging pulses, and a control module that adjusts the configuration of the current component of the charging pulses to maintain the voltage component in a range between the quiescent voltage and the maximum voltage in response to the monitored battery parameter. Charging and discharging pulses are alternated during the charging cycle. The published patent application further discloses a temperature sensing charger in which the charge discharge cycle is further regulated based upon the detected temperature of the battery. The main disadvantage of this system is that it does not have a high recovery efficiency for different battery states restored in the battery during an initial period of operation.
U.S. Pat. No. 7,557,541, to Marinka-Tóth et al., discloses a charging method by which the molecular movements in the cells of the rechargeable battery can be accelerated. Through this process, the time necessary for the chemical transformations and the time necessary for the full charge itself can be reduced. In that patent, there are different charging intervals inserted into the charging current, namely interval “a,” which is a pulsed charging interval, followed by an interval “e,” which is a charging interval with a continuous charging current. That patent discloses using a short discharge interval prior to charging to increase a battery's charge take-up capacity. That patent also monitors the internal resonance of the battery.
U.S. Pat. No. 6,856,118, to Lindqvist et al., discloses a battery charging system using hardware, software, and microcomputers to control the charging of the battery. Per that disclosure, temperature and conductivity measurements are additionally taken to control the battery charging. That patent regards a regeneration process for a battery, first to regenerate the chemical storage capacity, then to discharge the battery, and finally to recharge the battery. That patent also discloses a network and data storage system for the batteries to track their maintenance over time.
U.S. Pat. No. 6,504,344, to Adams et al., discloses a system for determining the health of a battery with multiple modules by measuring the health of each module, performing a discharge of each module, and then recharging each module, progressing from one module to the next. That disclosure takes into account the temperature of the battery or battery modules when performing the health measurement, as well as the charge and discharge cycles. That disclosure may offer the possibility of individual equalization of the individual cells in the battery, but that possibility requires a connection to the current lead battery as an additional charge source. Modern batteries do not always have access to current lead so the use of the method as disclosed by Adams et al. is limited to specific battery types.
In general, thyristors are unidirectional half-controlled electric wrenches. Thyristors can be forced open, and they close automatically if the current in its power circuit becomes less than the current retention. The main advantage of thyristors is their high overload capacity: 10-30 fold excess of the limit (shock) on current workers. The consequence of this is the high reliability of the devices formed on thyristors. The main drawback of a thyristor, however, is the complexity of the forced locking.
To improve the reliability of the operation of thyristor devices, developers prefer to provide a natural lock thyristor (transitions through zero voltage in the power supply). Torque control switching thyristor systems provide pulse-phase control, which controls the switching pulse delay with respect to the thyristor at a zero crossing in the mainstream voltage. This control principle is widely used in thyristor controlled rectifiers and inverters, i.e., the slave network. The latter term implies that the inverter thyristors provide natural commutation, i.e., they are locked under the influence of the mainstream voltage.
However, even when the battery charge is necessary to form a reverse current, i.e., to provide a consistently performing thyristor rectifier and inverter driven network, the design still cannot allow the simultaneous operation of a thyristor rectifier and inverter, as this will lead to a short circuit in the network via the thyristors. Thus, such operation is possible only after the closing of one or the other thyristor. The minimum pulse repetition period of the reverse current is 70-80 ms (depending on the frequency of the current in the network), which is higher than the desired value in methods for battery charging and maintenance. The present invention address this problem of the minimum pulse repetition period.